JPS61184906A - Ssb demodulation system - Google Patents

Abstract

PURPOSE:To obtain a high quality demodulation signal by eliminating distortion at a demodulation section so as to increase the carrier level. CONSTITUTION:A modulation wave formed by adding a carrier to an SSB (single side band) signal is received at the reception side, the signal passes through an amplitude limiter to reject the amplitude distortion caused at a propagation line, undergoes frequency detection and equalization of -6dB/oct to reproduce the original signal and the demodulated signal is led to a signal input terminal 1. Then the signal is divided into four; one of them is led to a Hilbert converter 2. The output of the Hilbert converter 2 is divided further into two, and a signal from an input signal terminal 1 is used to form a difference and a sum signal by a substraction circuit 3 and an addition circuit 4 respectively. Outputs of the substractor circuit 3 and the addition circuit 4 are inputted and multiplied by a multiplication circuit 5. On the other hand, one of the input signal divided into four passes through a delay circuit 6 and added to the output of the multiplication circuit 5 by an addition circuit 7 and the result is outputted. Moreover, the delay time of the delay circuit 6 is decided so that the distortion component included in the signal at an output signal terminal 8.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、伝ばん路で受けた振幅歪を除去するために、
復調部で振幅制限器が用いられるＳＳＢ変復調方式にお
ける復調信号に含まれる歪を１除去するための回路方式
に関するものである。[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for removing amplitude distortion received in a propagation path.
The present invention relates to a circuit system for removing distortion included in a demodulated signal in an SSB modulation/demodulation method in which an amplitude limiter is used in a demodulation section.

〔従来技術と問題点〕[Prior art and problems]

送信側で音声信号でＳＳＢｇｉ調した後、これに搬送波
を付与して送信信号となし、受信側で信号を受信した後
振幅制限器を用いてその振幅を一定にしてから周波数検
波するごとく構成された通信系においては、復調信号の
歪を小さくするために、ＳＳＢ信号レベルに比べて搬送
波レベルを大きくする必要があった。After SSBgi modulating the audio signal on the transmitting side, a carrier wave is added to it to make it a transmitted signal, and after receiving the signal on the receiving side, the amplitude is made constant using an amplitude limiter, and then frequency detection is performed. In such communication systems, it was necessary to make the carrier wave level higher than the SSB signal level in order to reduce the distortion of the demodulated signal.

しかし、搬送波は直接情報を伝送していないから、この
ような方式においては、変調信号における情報伝送効率
が低いという欠点があった。However, since the carrier wave does not directly transmit information, such a system has the disadvantage that the information transmission efficiency in the modulated signal is low.

〔発明の目的〕[Purpose of the invention]

本発明では、これらの欠点を除去するために、復調部で
歪の除去を図るもので、搬送波レベルを大とすることな
く高質な復調信号を得ることのできる復調方式を提供す
ることを目的としている。In order to eliminate these drawbacks, the present invention aims to eliminate distortion in the demodulation section, and an object of the present invention is to provide a demodulation method that can obtain a high-quality demodulated signal without increasing the carrier wave level. It is said that

以下、本発明の構成等に関し、実施例の図面に基づいて
詳細に説明する。Hereinafter, the configuration of the present invention will be described in detail based on the drawings of the embodiments.

〔実施例〕〔Example〕

第１図は本発明の一実施例のブロック図であって、１は
信号入力端子、２はヒルベルト変換器、３は減算回路、
４は加算回路、５は掛算回路、６は遅延回路、７は加算
回路、８は出力信号端子を表わしている。FIG. 1 is a block diagram of an embodiment of the present invention, in which 1 is a signal input terminal, 2 is a Hilbert transformer, 3 is a subtraction circuit,
4 represents an adder circuit, 5 a multiplication circuit, 6 a delay circuit, 7 an adder circuit, and 8 an output signal terminal.

受信側において、ＳＳＢ　（下側波帯）信号に搬送波を
付加した変調波を受信し、伝ばん路で受けた振幅歪を除
去するために振幅制限器を通してから周波数検波して、
更に、−６ｄＢ１０ｃｔの等化を行なうことにより原信
号を再生して、この復調信号を第１図の信号入力端子１
に導く。On the receiving side, a modulated wave obtained by adding a carrier wave to an SSB (lower sideband) signal is received, passed through an amplitude limiter to remove amplitude distortion received in the propagation path, and then frequency detected.
Furthermore, the original signal is reproduced by performing equalization of -6dB10ct, and this demodulated signal is sent to the signal input terminal 1 in Fig. 1.
lead to.

そして、該信号は四分割し、その内の一つは、ヒルベル
ト変換器２に導入する。The signal is then divided into four parts, one of which is introduced into the Hilbert transformer 2.

ヒルベルト変換器２の出力は、更に二分割して、入力信
号端子１からの信号との間で減算回路３と加算回路４で
、それぞれ差、および和の信号を作る。減算回路３およ
び加算回路４の出力を入力として掛算回路５で掛算する
。The output of the Hilbert transformer 2 is further divided into two parts, and a subtraction circuit 3 and an addition circuit 4 generate a difference signal and a sum signal between the output signal and the signal from the input signal terminal 1, respectively. The outputs of the subtraction circuit 3 and addition circuit 4 are inputted and multiplied by a multiplication circuit 5.

一方、四分割された入力信号野の内の一つは遅１延回路
６を通って、加算回路７で掛算回路５の出力との和を求
め、これが出力となる。On the other hand, one of the four divided input signal fields passes through the delay circuit 6 and is summed with the output of the multiplication circuit 5 in the addition circuit 7, which becomes the output.

遅延回路６の遅延時間は、出力信号端子８の信号に含ま
れる歪成分が最小になるように決める。The delay time of the delay circuit 6 is determined so that the distortion component contained in the signal at the output signal terminal 8 is minimized.

次に、数式を用いて本発明の動作原理をくわしく説明す
る。Next, the operating principle of the present invention will be explained in detail using mathematical formulas.

まず音声償号惺（１）を ｍ（ｔ）＝　ｆ（ｔ）　十ｊ　ｆ（ｔ）と解析信号で表
わす。First, the speech compensation equation (1) is expressed as an analytic signal as m(t)=f(t) j f(t).

ｆ（ｔ）はｆ（ｔ）のヒルベルト変換対である。f(t) is the Hilbert transform pair of f(t).

搬送波角周波数を　ω。とすると、Ｓ　Ｓ　Ｂ信号プラ
ス搬送波出力ｓ　（Ｂは Ｓ　（ｔ）＝　ＣｅＯ８（ＩＪ　ｏｔ＋　ｆ（ｔ）ｃｏ
ｓｃ＋Ｊ　ｏｔ十ｆ（ｔ）ｓｉｎａ＋　、ｔ＝　Ａ　ｃ
ｏｓ　（ωｏｔ−ω（ｔ）　）と書ける。ここで ω　（ｔ）　　　＝ａｒｃｔａｎ　　　　ｆ（ｔ）／　
　（Ｃ−ト　ｆ（ｔ）　　　）である、振幅制限器が用
いられるには、Ｃ＞　Ｉｆ（ｔ）ｌ　　、　　Ｉｆ（ｔ
）ｌを満たす必要がある。The carrier angular frequency is ω. Then, S S B signal plus carrier wave output s (B is S (t) = CeO8 (IJ ot + f (t) co
sc+J otf(t)sina+ , t= A c
It can be written as os (ωot-ω(t)). Here ω (t) = arctan f(t)/
(C-t f(t) ), in order to use an amplitude limiter, C> If(t)l , If(t
)l must be satisfied.

振幅制限器出力を周波数検波器に通した出力ｅ（ｔ）は ｄω ｅ　（ｔ）＝ω。−□ ｔ この出力を一６ｄＢ１０ａｔで等化するととなる。ＤＣ
成分（ω０）を除いた信号を端子１に導（。The output e(t) obtained by passing the amplitude limiter output through a frequency detector is dω e (t)=ω. -□t If this output is equalized by -6dB10at, then it becomes. D.C.
The signal excluding the component (ω0) is led to terminal 1 (.

従って、端子１での信号成分は、 で１ある。Therefore, the signal component at terminal 1 is There is 1.

ユニで初項−ｆ（ｔ）／　Ｃが信号の主成分であるから
、これをもとにしてｌＩｐ＆１図に示した実施例につい
て、動作を説明すると、各信号は、それぞれ、−ｆ（ｔ
）／Ｃのヒルベルト変換器出力は−ｆ（ｔ）／Ｃとなり
、減算回路３の出力は（−ｆ（Ｌ）／Ｃ）十〇（ｔ）／
Ｃ）、加算回路４の出力は−（（↑（ｔ）／Ｃ）＋（ｆ
（ｔ）／　Ｃ））となる。Since the first term -f(t)/C is the main component of the signal, based on this, the operation of the embodiment shown in FIG.
)/C's Hilbert transformer output is -f(t)/C, and the output of the subtraction circuit 3 is (-f(L)/C) 10(t)/
C), the output of the adder circuit 4 is -((↑(t)/C)+(f
(t)/C)).

この２出力を掛算回路５で演算すると、出力は（（ｆ（
ｔ）／　Ｃ）−（ｆ（ｔ）／　Ｃ））（（ｆ（ｔ）／　
Ｃ）＋（ｆｍ／　Ｃ））＝　（ｆ（ｔ）／　Ｃ）”−（
ｆ（ｔ）／　Ｃ）”　となる。When these two outputs are calculated by the multiplication circuit 5, the output is ((f(
t)/C)-(f(t)/C))((f(t)/
C)+(fm/C))=(f(t)/C)"-(
f(t)/C)".

この出力を（１）式に加えると −（ｆ（ｔ）／Ｃ）”十〇　（Ｃ−’）＝（−ｆ（ｔ）
／　Ｃ）十〇　（Ｃ−コ）となり、２大の歪が除去でき
る。Adding this output to equation (1), -(f(t)/C)"10 (C-')=(-f(t)
/ C) 10 (C-co), and two major distortions can be removed.

遅延回路６は掛算回路５の出力までに信号が種々の回路
を通るために生ずる遅延時間に合うように主信号を遅延
させるもので２次の歪が最小になるように遅延時間を設
定する。The delay circuit 6 delays the main signal to match the delay time caused by the signal passing through various circuits before being output from the multiplication circuit 5, and sets the delay time so that second-order distortion is minimized.

なお、上述の説明に用いた数式からも明らかなように、
本発明と同等の機能の実現手段として、復調信号を二乗
した信号と該復調信号をヒルベルト変換した信号を二乗
した信号との差の信号と、前記復調信号を一定時間遅延
せしめた信号とを加算することにより出力を得る構成を
採ることもできる。Furthermore, as is clear from the formula used in the above explanation,
As a means for realizing a function equivalent to that of the present invention, a signal representing the difference between a signal obtained by squaring a demodulated signal and a signal obtained by squaring a signal obtained by Hilbert-transforming the demodulated signal, and a signal obtained by delaying the demodulated signal by a certain period of time are added. It is also possible to adopt a configuration in which output is obtained by doing this.

しかし、一般に掛算回路（二乗は掛算回路で行なう）は
、構成が複雑であって、特にそれを上述の構成のように
複数組設けた場合には、各掛算回路の特性の差を補償す
るための整合等が必要となり取り扱いが極めて繁雑とな
るうえ、良好な結果が期待できない。However, multiplier circuits (squaring is performed by the multiplier circuit) generally have a complex configuration, and especially when multiple sets are provided as in the above configuration, it is necessary to compensate for differences in the characteristics of each multiplier circuit. It is extremely complicated to handle as it requires matching, etc., and good results cannot be expected.

不発明は、実施例にも見られるように、掛算回路は１組
設けるのみで良く、従って、取り扱いが容易で良好な特
性を有する回路を実現し得るものである。The advantage of the present invention is that, as seen in the embodiments, only one set of multiplication circuits is required, and therefore a circuit that is easy to handle and has good characteristics can be realized.

〔発明の効果〕〔Effect of the invention〕

以上説明したように、本発明の方式によれば、再１生信
号に含まれる歪を除去することが可能で、特に、聰感上
耳ざわりになる原音の２倍の周波数成分を除去すること
ができるから、復調音声品質が改善される。また、歪除
去回路がない場合には搬送波レベルを高めることによっ
て復調音声の歪率を低くしなければならなかったが、本
発明の方式によれば、従来のように搬送波レベルを高（
する必要がないから、情報伝送効率を高めることができ
る利点がある。As explained above, according to the method of the present invention, it is possible to remove the distortion contained in the reproduced signal, and in particular, it is possible to remove the frequency component twice that of the original sound, which is harsh on the ears. As a result, demodulated audio quality is improved. Furthermore, in the absence of a distortion removal circuit, it was necessary to lower the distortion rate of demodulated audio by increasing the carrier wave level, but according to the method of the present invention, the carrier wave level is raised (
Since there is no need to do this, there is an advantage that information transmission efficiency can be increased.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は、本発明の一実施例のブロック図である。 FIG. 1 is a block diagram of one embodiment of the present invention.

Claims (1)

【特許請求の範囲】[Claims] 送信側で音声信号でＳＳＢ変調した後、これに搬送波を
付与して送信信号となし、受信側で信号を受信した後、
振幅制限器を用いてその振幅を一定にしてから周波数検
波するごとく構成された通信系において、復調信号と該
復調信号をヒルベルト変換して得た信号との和および差
を求め、該和の信号と差の信号とを掛算して得た信号と
、前記復調信号を一定時間遅延せしめた信号とを加算す
ることにより出力を得ることを特徴とするＳＳＢ復調方
式。After SSB modulation with the audio signal on the transmitting side, a carrier wave is added to it to make it a transmitted signal, and after receiving the signal on the receiving side,
In a communication system configured to use an amplitude limiter to make the amplitude constant and then perform frequency detection, the sum and difference of the demodulated signal and the signal obtained by Hilbert transformation of the demodulated signal are calculated, and the sum signal is An SSB demodulation method characterized in that an output is obtained by adding a signal obtained by multiplying a signal by a difference signal and a signal obtained by delaying the demodulated signal by a certain period of time.